Null data packet (NDP) ranging with unassociated stations

ABSTRACT

An access point (AP) device of a wireless communication network determines that an unassociated client station requests to participate in a ranging measurement procedure with the AP device, and determines a preliminary network ID for uses by the unassociated client station during a ranging measurement session and while the unassociated client station remains unassociated with the wireless communication network. The AP device transmits a packet having the preliminary network ID, and after transmitting the packet having the preliminary network ID, participates in a multi-user (MU) null data packet (NDP) ranging measurement session with a plurality of client stations that includes the unassociated client station. Participating in the MU NDP ranging measurement session includes transmitting a trigger frame to prompt the plurality of client stations to simultaneously transmit respective NDPs as part of an uplink MU transmission corresponding to the MU NDP ranging measurement session, where the trigger frame includes the preliminary network ID.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication entitled “NULL DATA PACKET (NDP) RANGING WITH UNASSOCIATEDSTATIONS”, having a serial number of Ser. No. 15/987,716, having afiling date of May 23, 2018; which claims the benefit of the U.S.provisional application entitled “NULL DATA PACKET (NDP) RANGING FORUNASSOCIATED STAs”, having a serial number of 62/510,118, and having afiled date of May 23, 2017, having common inventors, and having a commonassignee, all of which is incorporated by reference in its entirety.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly to communication exchanges betweenwireless communication devices for ranging measurements among thewireless communication devices.

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pastdecade, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data throughput. For example, the IEEE 802.11bStandard specifies a single-user peak throughput of 11 megabits persecond (Mbps), the IEEE 802.11a and 802.11g Standards specify asingle-user peak throughput of 54 Mbps, the IEEE 802.11n Standardspecifies a single-user peak throughput of 600 Mbps, and the IEEE802.11ac Standard specifies a single-user peak throughput in thegigabits per second (Gbps) range. Future standards promise to provideeven greater throughput, such as throughputs in the tens of Gbps range.

Some mobile communication devices include a WLAN network interface andsatellite positioning technology, such as global positioning system(GPS) technology. GPS technology in mobile communication devices isuseful for navigating to a desired location, for example. However, GPStechnology does not typically provide accurate location information whena GPS receiver is not in direct sight of a GPS satellite, and thus GPStechnology is often not useful for providing location information whilea mobile communication device is within a building such as an airport, ashopping mall, etc., within a tunnel, etc.

Techniques for determining a position of a communication device usingWLAN technology are now under development. For example, a distancebetween a first communication and a second communication device isdetermined by measuring a time of flight of WLAN transmissions betweenthe first communication device and the second communication device, andthe determined distance. Similarly, distances between the firstcommunication device and multiple third communication devices aredetermined. Then, the determined distances are used to estimate alocation of the first communication device by employing, for example, atriangulation technique. For a first communication device havingmultiple antennas, an angle of departure (AoD) of a WLAN transmissioncan be determined. Similarly, for a second communication device havingmultiple antennas, an angle of arrival (AoA) of the WLAN transmissionfrom the first communication device can be determined. The AoD and theAoA, along with the determined distances, can be also be used forestimating the location of the first communication device.

SUMMARY

In an embodiment, a method is for performing a ranging measurementprocedure, and includes: determining, at an access point (AP) device ofa wireless communication network, that an unassociated client stationrequests to participate in a ranging measurement procedure with the APdevice, wherein the unassociated client station is not currentlyassociated with the wireless communication network and has not beenassigned, by the AP device, a network identifier (ID) as a result ofbecoming associated with the wireless communication network;determining, at the AP device, a preliminary network ID for theunassociated client station, the preliminary network ID to be used bythe unassociated client station during a ranging measurement sessionwhile the unassociated client station remains not associated with thewireless communication network; transmitting, by the AP device, a packethaving the preliminary network ID, wherein the packet indicates that theAP device has assigned the preliminary network ID to the unassociatedclient station for use during the ranging measurement session; and aftertransmitting the packet having the preliminary network ID, participatingin, by the AP device, a multi-user (MU) null data packet (NDP) rangingmeasurement session with a plurality of client stations that includesthe unassociated client station, wherein participating in the MU NDPranging measurement session includes transmitting a trigger frame toprompt the plurality of client stations to simultaneously transmitrespective NDPs as part of an uplink MU transmission corresponding tothe MU NDP ranging measurement session, wherein the trigger frameincludes the preliminary network ID to prompt the unassociated clientstation to transmit an NDP as part of the uplink MU transmission.

In another embodiment, an apparatus comprises a network interface deviceassociated with an access point (AP) device of a wireless communicationnetwork. The network interface device includes one or more integratedcircuits (ICs), and is configured to: determine that an unassociatedclient station requests to participate in a ranging measurementprocedure with the AP device, wherein the unassociated client station isnot currently associated with the wireless communication network and hasnot been assigned, by the AP device, a network identifier (ID) as aresult of becoming associated with the wireless communication network;determine a preliminary network ID for the unassociated client station,the preliminary network ID to be used by the unassociated client stationduring a ranging measurement session while the unassociated clientstation remains not associated with the wireless communication network;transmit a packet having the preliminary network ID, wherein the packetindicates that the AP device has assigned the preliminary network ID tothe unassociated client station for use during the ranging measurementsession; and after transmitting the packet having the preliminarynetwork ID, participate in a multi-user (MU) null data packet (NDP)ranging measurement session with a plurality of client stations thatincludes the unassociated client station, wherein participating in theMU NDP ranging measurement session includes transmitting a trigger frameto prompt the plurality of client stations to simultaneously transmitrespective NDPs as part of an uplink MU transmission corresponding tothe MU NDP ranging measurement session, wherein the trigger frameincludes the preliminary network ID to prompt the unassociated clientstation to transmit an NDP as part of the uplink MU transmission.

In yet another embodiment, a method is for performing a rangingmeasurement procedure, and includes: receiving, at a first communicationdevice, a packet having a preliminary network identifier (ID), whereinthe packet indicates that an access point (AP) device of a wirelesscommunication network has assigned the preliminary network ID to thefirst communication device for use during a ranging measurement session,wherein the first communication device is not currently associated withthe wireless communication network and has not been assigned, by the APdevice, a network ID as a result of becoming associated with thewireless communication network; and after receiving the packet havingthe preliminary network ID, participating in, by the first communicationdevice, a multi-user (MU) null data packet (NDP) ranging measurementsession with the AP device. Participating in the MU NDP rangingmeasurement session includes: receiving, at the communication device, atrigger frame configured to prompt a plurality of communication device,including the first communication device, to simultaneously transmitrespective NDPs as part of an uplink MU transmission corresponding tothe MU NDP ranging measurement session, wherein the trigger frameincludes the preliminary network ID to prompt the first communicationdevice to transmit a first NDP as part of the uplink MU transmission;and in response to the trigger frame, transmitting, by the firstcommunication device, the first NDP as part of the uplink MUtransmission.

In still another embodiment, an apparatus comprises a network interfacedevice associated with a first communication device. The networkinterface device includes one or more integrated circuits (ICs), and isconfigured to: receive a packet having a preliminary network identifier(ID), wherein the packet indicates that an access point (AP) device of awireless communication network has assigned the preliminary network IDto the first communication device for use during a ranging measurementsession, wherein the first communication device is not currentlyassociated with the wireless communication network and has not beenassigned, by the AP device, a network ID as a result of becomingassociated with the wireless communication network; and after receivingthe packet having the preliminary network ID, participate in amulti-user (MU) null data packet (NDP) ranging measurement session withthe AP device. The network interface device is also configured to, aspart of participating in the MU NDP ranging measurement session: receivea trigger frame configured to prompt a plurality of communicationdevice, including the first communication device, to simultaneouslytransmit respective NDPs as part of an uplink MU transmissioncorresponding to the MU NDP ranging measurement session, wherein thetrigger frame includes the preliminary network ID to prompt the firstcommunication device to transmit a first NDP as part of the uplink MUtransmission; and in response to the trigger frame, transmit the firstNDP as part of the uplink MU transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment.

FIG. 2A is a diagram of an example multi-user (MU) ranging measurementexchange in an MU ranging measurement procedure, according to anembodiment.

FIG. 2B is a timing diagram of the example MU ranging measurementexchange of FIG. 2A, according to an embodiment.

FIG. 3 is a timing diagram of an example MU ranging measurementprocedure, according to an embodiment.

FIG. 4 is a timing diagram of an example MU ranging measurementprocedure, according to an embodiment.

FIG. 5A is a diagram of an example information element for assigning apreliminary network identifier (ID) to an unassociated client stationfor use during an MU ranging measurement procedure, according to anembodiment.

FIG. 5B is a diagram of another example information element forassigning a preliminary network ID to an unassociated client station foruse during an MU ranging measurement procedure, according to anotherembodiment.

FIG. 6 is a timing diagram of another example MU ranging measurementprocedure, according to another embodiment.

FIG. 7 is an example frame format of a request frame regarding an MUranging measurement procedure, according to an embodiment.

FIG. 8A is an example frame format of a response frame regarding an MUranging measurement procedure, according to an embodiment.

FIG. 8B is a diagram of an example information element for assigning apreliminary network ID to an unassociated client station for use duringan MU ranging measurement procedure, according to an embodiment.

FIG. 8C is an example format of contents of a frame body of the responseframe of FIG. 8A, according to another embodiment.

FIG. 9 is a timing diagram of another example MU ranging measurementprocedure, according to another embodiment.

FIG. 10 is a timing diagram of another example MU ranging measurementprocedure, according to another embodiment.

FIG. 11A is an example frame format of a response frame regarding an MUranging measurement procedure, according to an embodiment.

FIG. 11B is a diagram of an example information element for assigning apreliminary network ID to an unassociated client station for use duringan MU ranging measurement procedure, according to an embodiment.

FIG. 12 is a flow diagram of an example method for participating in anMU ranging measurement procedure, according to an embodiment.

FIG. 13 is a flow diagram of another example method for participating inan MU ranging measurement procedure, according to another embodiment.

DETAILED DESCRIPTION

Ranging measurement procedures and techniques described below arediscussed in the context of wireless local area networks (WLANs) thatutilize protocols the same as or similar to protocols defined by the802.11 Standard from the Institute of Electrical and ElectronicsEngineers (IEEE) merely for explanatory purposes. In other embodiments,however, ranging measurement procedures and techniques are utilized inother types of wireless communication systems such as personal areanetworks (PANs), mobile communication networks such as cellularnetworks, metropolitan area networks (MANs), etc.

FIG. 1 is a block diagram of an example WLAN 110, according to anembodiment. The WLAN 110 includes an access point (AP) 114 thatcomprises a host processor 118 coupled to a network interface device122. The network interface 122 includes a medium access control (MAC)processor 126 and a physical layer (PHY) processor 130. The PHYprocessor 130 includes a plurality of transceivers 134, and thetransceivers 134 are coupled to a plurality of antennas 138. Althoughthree transceivers 134 and three antennas 138 are illustrated in FIG. 1,the AP 114 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 134 and antennas 138 in other embodiments. In someembodiments, the AP 114 includes a higher number of antennas 138 thantransceivers 134, and antenna switching techniques are utilized.

The network interface 122 is implemented using one or more integratecircuits (ICs) configured to operate as discussed below. For example,the MAC processor 126 may be implemented, at least partially, on a firstIC, and the PHY processor 130 may be implemented, at least partially, ona second IC. As another example, at least a portion of the MAC processor126 and at least a portion of the PHY processor 130 may be implementedon a single IC. For instance, the network interface 122 may beimplemented using a system on a chip (SoC), where the SoC includes atleast a portion of the MAC processor 126 and at least a portion of thePHY processor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the networkinterface 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 may be configured to generate MAC layerdata units such as MAC service data units (MSDUs), MAC protocol dataunits (MPDUs), etc., and provide the MAC layer data units to the PHYprocessor 130. The PHY processor 130 may be configured to receive MAClayer data units from the MAC processor 126 and encapsulate the MAClayer data units to generate PHY data units such as PHY protocol dataunits (PPDUs) for transmission via the antennas 138. Similarly, the PHYprocessor 130 may be configured to receive PHY data units that werereceived via the antennas 138, and extract MAC layer data unitsencapsulated within the PHY data units. The PHY processor 130 mayprovide the extracted MAC layer data units to the MAC processor 126,which processes the MAC layer data units.

The PHY processor 130 is configured to downconvert one or more radiofrequency (RF) signals received via the one or more antennas 138 to oneor more baseband analog signals, and convert the analog basebandsignal(s) to one or more digital baseband signals, according to anembodiment. The PHY processor 130 is further configured to process theone or more digital baseband signals to demodulate the one or moredigital baseband signals and to generate a PPDU. The PHY processor 130includes amplifiers (e.g., a low noise amplifier (LNA), a poweramplifier, etc.), a radio frequency (RF) downconverter, an RFupconverter, a plurality of filters, one or more analog-to-digitalconverters (ADCs), one or more digital-to-analog converters (DACs), oneor more discrete Fourier transform (DFT) calculators (e.g., a fastFourier transform (FFT) calculator), one or more inverse discreteFourier transform (IDFT) calculators (e.g., an inverse fast Fouriertransform (IFFT) calculator), one or more modulators, one or moredemodulators, etc.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a readROM, a flash memory, etc. In an embodiment, the MAC processor 126includes a hardware state machine.

The WLAN 110 includes a plurality of client stations 154. Although threeclient stations 154 are illustrated in FIG. 1, the WLAN 110 includesother suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of client stations154 in various embodiments. The client station 154-1 includes a hostprocessor 158 coupled to a network interface device 162. The networkinterface 162 includes a MAC processor 166 and a PHY processor 170. ThePHY processor 170 includes a plurality of transceivers 174, and thetransceivers 174 are coupled to a plurality of antennas 178. Althoughthree transceivers 174 and three antennas 178 are illustrated in FIG. 1,the client station 154-1 includes other suitable numbers (e.g., 1, 2, 4,5, etc.) of transceivers 174 and antennas 178 in other embodiments. Insome embodiments, the client station 154-1 includes a higher number ofantennas 178 than transceivers 174, and antenna switching techniques areutilized.

The network interface 162 is implemented using one or more ICsconfigured to operate as discussed below. For example, the MAC processor166 may be implemented on at least a first IC, and the PHY processor 170may be implemented on at least a second IC. As another example, at leasta portion of the MAC processor 166 and at least a portion of the PHYprocessor 170 may be implemented on a single IC. For instance, thenetwork interface 162 may be implemented using an SoC, where the SoCincludes at least a portion of the MAC processor 166 and at least aportion of the PHY processor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the network interface 162 may be implemented on a singleIC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client device 154-1 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. The PHY processor 170 may be configured to receive MAClayer data units from the MAC processor 166 and encapsulate the MAClayer data units to generate PHY data units such as PPDUs fortransmission via the antennas 178. Similarly, the PHY processor 170 maybe configured to receive PHY data units that were received via theantennas 178, and extract MAC layer data units encapsulated within thePHY data units. The PHY processor 170 may provide the extracted MAClayer data units to the MAC processor 166, which processes the MAC layerdata units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1.Each of the client stations 154-2 and 154-3 has the same or a differentnumber of transceivers and antennas. For example, the client station154-2 and/or the client station 154-3 each have only two transceiversand two antennas (not shown), according to an embodiment.

PPDUs are sometimes referred to herein as packets. MPDUs are sometimesreferred to herein as frames.

FIG. 2A is a diagram of an example multi-user (MU) ranging measurementexchange 200 in an MU ranging measurement procedure, according to anembodiment. The diagram 200 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 2A are generated by other suitablecommunication devices in other suitable types of wireless networks.

The MU ranging measurement exchange 200 corresponds to an AP-initiatedMU ranging measurement exchange, according to an embodiment. The MUranging measurement exchange 200 includes an uplink (UL) null datapacket (NDP) frame exchange 204, a downlink (DL) NDP transmissionportion 208, a DL feedback (FB) frame exchange 210, and an UL FB frameexchange 212. In an embodiment, the uplink UL NDP frame exchange 204,the DL NDP transmission portion 208, the DL FB frame exchange 210, andthe UL FB frame exchange 212 occur within a single transmit opportunityperiod (TXOP). In another embodiment, the uplink UL NDP frame exchange204, the DL NDP transmission portion 208, the DL FB frame exchange 210,and the UL FB frame exchange 212 do not occur within a single TXOP. Forexample, the uplink UL NDP frame exchange 204 and the DL NDPtransmission portion 208 occur within a single TXOP, whereas the DL FBframe exchange 210 and the UL FB frame exchange 212 occur after thesingle TXOP (e.g., in another TXOP or in multiple other TXOPs).

In the UL NDP exchange 204, a first communication device (e.g., the AP114) transmits a DL PPDU 216 that includes a trigger frame to cause agroup of multiple second communication devices (e.g., client stations154) to simultaneously transmit, as part of an uplink (UL) MUtransmission 220, UL null data packets (NDPs) 224. In an embodiment, thetrigger frame in the PPDU 216 is a type of trigger frame specificallyfor initiating an MU ranging measurement exchange such as the MU rangingmeasurement exchange 200. The trigger frame in the PPDU 216 causesmultiple client stations 154 to begin simultaneously transmitting the ULMU transmission 220 a defined time period after an end of the PPDU 216.In an embodiment, the defined time period is a short interframe space(SIFS) as defined by the IEEE 802.11 Standard. In other embodiments,another suitable time period is utilized.

In an embodiment, the UL MU transmission 220 includes an UL MU multipleinput, multiple output (MIMO) transmission having two or more UL NDPs224 from multiple client stations 154, e.g., STA1, STA2, STA3, and STA4.The two or more of the UL NDPs 224 are transmitted within a samefrequency band via different spatial streams (e.g., MU-MIMO). In anotherembodiment, the UL MU transmission 220 includes an UL orthogonalfrequency division multiple access (OFDMA) transmission having two ormore UL NDPs 224 from multiple client stations 154, e.g., STA1, STA2,STA3, and STA4, in different respective frequency bandwidth portions. Inyet another embodiment, three or more UL NDP packets 224 transmittedusing a combination of UL MU-MIMO and UL OFDMA, where at least two NDPsare transmitted using MU-MIMO in a same frequency bandwidth portion viadifferent spatial streams, and at least one NDP is transmitted in atleast one other different frequency bandwidth portion. The UL NDPs 224include PHY preambles having one or more short training fields (STFs),one or more long training fields (LTFs) and one or more signal fields,in an embodiment. The UL NDPs 224 omit data portions.

When transmitting the UL NDPs 224, each client station 154 records atime t_(1,k) at which the client station 154 began transmitting the ULNDP 224, where k is an index indicating the particular client station154. Similarly, when the AP 114 receives each UL NDP 224, the AP 114records a time t_(2,k) at which the AP 114 began receiving the UL NDP224.

In some embodiments, when transmitting the UL NDPs 224, each of at leastsome of the client stations 154 (e.g., client stations 154 with multipleantennas 174) records an angle of departure, AoD_(1,k), at which the ULNDP 224 left the antennas 178 of the client station 154. Similarly, whenthe AP 114 receives each UL NDP 224, the AP 114 records an angle ofarrival, AoA_(1,k), at which the UL NDP 224 arrived at the antennas 138of the AP 114.

FIG. 2B is a timing diagram of the example MU ranging measurementexchange 200 of FIG. 2A. As illustrated in FIG. 2B, each client station154 records the time t_(1,k) at which the client station 154 begantransmitting the UL NDP 224, and records the AoD_(1,k) at which the ULNDP 224 left the antennas 178 of the client station 154. Additionally,the AP 114 records the time t_(2,k) at which the AP 114 began receivingeach UL NDP 224, and the AoA_(1,k), at which each UL NDP 224 arrived atthe antennas 138 of the AP 114.

Referring now to FIGS. 2A and 2B, responsive to the UL MU transmission220, the AP 114 begins transmitting a DL PPDU 228 that includes an NDPannouncement (NDPA) frame a defined time period after an end of the ULMU transmission 220. In an embodiment, the defined time period is SIFS.In other embodiments, another suitable time period is utilized. The NDPAframe in the PPDU 228 is configured to cause the client stations 154 tobe prepared to receive an NDP from the AP 114, according to anembodiment.

The AP 114 generates a DL PPDU 232 and begins transmitting the DL PPDU232 a defined time period after an end of the DL PPDU 228. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The DL PPDU 232 is a MU PPDUthat includes DL NDPs 236 to respective client stations 154. In anotherembodiment, the AP 114 transmits a single DL NDP 236 using a SU DLtransmission (e.g., with a broadcast destination address) to the clientstations 154. The DL NDP(s) 236 include PHY preamble(s) having one ormore STFs, one or more LTFs and one or more signal fields, in anembodiment. The DL NDP(s) 236 omit data portions. In an embodiment,different DL NDPs 236 are transmitted in different frequency bandwidthportions (e.g., OFDMA). In some embodiments, two or more of the DL NDPs236 are transmitted within a same frequency band (e.g., two or more ofthe DL NDPs 236 span the same frequency band) using different spatialstreams (e.g., the two or more DL NDPs 236 are transmitted usingMU-MIMO). In another embodiment, a single DL NDP 236 is broadcast to theclient stations 154.

When transmitting the DL NDP(s) 236, the AP 114 records a time t_(3,k)at which the AP 114 began transmitting the DL NDP(s) 236. Similarly,when each client station 154 receives the corresponding DL NDP 236, theclient station 154 records a time t_(4,k) at which the client station154 began receiving the DL NDP 236. As illustrated in FIG. 2B, the AP114 records the time t_(3,k) at which the AP 114 began transmitting theDL NDP 236, and the client station 154 records the time t_(4,k) at whichthe client station 154 began receiving the DL NDP 236.

In some embodiments, when transmitting the DL NDP 236, the AP 114records an AoD_(2,k) at which the DL NDP 236 left the antennas 138 ofthe AP 114. Similarly, when the client station 154 receives the DL NDP236, the client station 154 records an AoA_(2,k) at which the DL NDP 236arrived at the antennas 178 of the client station 154.

In some embodiments, the MU ranging measurement exchange 200 omits theDL PPDU 228. For example, the AP 114 begins transmitting the DL PPDU 232a defined time period after an end of the UL MU transmission 220. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

The DL FB exchange 210 includes a DL PPDU 240 (which may be a DL OFDMAtransmission or a DL MU-MIMO transmission) having FB frames 244 formultiple client stations 154, e.g., STA1, STA2, STA3, and STA4. The FBframes 244 are illustrated in FIG. 2A as being transmitted in differentfrequency bandwidth portions. In some embodiments, two or more of the FBframes 244 are transmitted within a same frequency band (e.g., two ormore of the FB frames 244 span the same frequency band) using differentspatial streams (e.g., the two or more FB frames 244 are transmittedusing MU-MIMO).

In some embodiments, the DL PPDU 240 is transmitted a defined timeperiod after an end of the DL PPDU 232. In an embodiment, the definedtime period is SIFS. In other embodiments, another suitable time periodis utilized. In other embodiments, the DL PPDU 240 is transmitted aftersome delay. As discussed above, in some embodiments, the DL PPDU 240 isnot transmitted within a same TXOP as the DL PPDU 232.

The FB frames 244 respectively include the recorded times t_(2,k) andt_(3,k). In some embodiments, each of one or more FB frames 244respectively includes (optionally) the recorded angles AoA_(1,k) andAoD_(2,k). In some embodiments, the FB frames 244 optionally alsoinclude respective channel estimate information determined by the AP 114based on reception of the UL NDPs 224.

After receipt of the FB frames 244, one or more of the client stations154 respectively calculate one or more respective of times-of-flightbetween the AP 114 and the one or more client stations 154 using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k), according to anembodiment. Any suitable technique, including currently knowntechniques, may be utilized to calculate a time-of-flight using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k). Respectivedistances between the AP 114 and the client stations 154 may becalculated using the calculated times-of-flight, e.g., by respectivelymultiplying the times-of-flight by the speed of light, according to anembodiment.

In some embodiments, one or more of the client stations 154 calculatesestimated positions of one or more of the client stations using thecalculated times-of-flight. For example, the client station 154-1 usestriangulation techniques to calculate an estimated positions of theclient station 154-1 using the calculated time-of-flight. In someembodiments, the client station 154-1 calculates an estimated positionof the client station also using the recorded angles AoD_(1,k),AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, the recorded anglesAoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are used as part of atriangulation algorithm for determining a position of the client station154-1.

Responsive to receipt of the FB frames 244, the client stations 154generate an UL MU transmission 250 (which may be an UL OFDMAtransmission or an UL MU MIMO transmission) that includes respective ACKframes 254 from respective client stations, according to an embodiment.The client stations 154 transmit as part of the UL MU transmission 250 adefined time period after an end of the DL transmission 240. In anembodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized. The ACK frames 254 areillustrated in FIG. 2A as being transmitted in different frequencybandwidth portions. In some embodiments, two or more of the ACK frames254 are transmitted within a same frequency band (e.g., two or more ofthe ACK frames 254 span the same frequency band) using different spatialstreams (e.g., the two or more ACK frames 254 are transmitted usingMU-MIMO). In some embodiments, the client stations 154 do not generateand transmit the UL MU transmission 250 (e.g., the client stations 154do not generate and transmit the AC frames 254).

In an embodiment, the AP 114 transmits a DL PPDU 260 a defined timeperiod after an end of the UL MU transmission 250. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized. The PPDU 260 includes a trigger frame to cause thegroup of client stations 154 to simultaneously transmit, as part of anUL MU transmission 264, uplink PPDUs 268 that include rangingmeasurement feedback. The trigger frame in the PPDU 260 causes multipleclient stations 154 to begin simultaneously transmitting the UL MUtransmission 264 a defined time period after an end of the PPDU 260. Inan embodiment, the defined time period is SIFS. In other embodiments,another suitable time period is utilized.

The UL MU transmission 264 (which may be an UL OFDMA transmission or anUL MU-MIMO transmission) includes UL PPDUs 268 from multiple clientstations 154, e.g., STA1, STA2, STA3, and STA4. The UL PPDUs 268 areillustrated in FIG. 2A as being transmitted in different frequencybandwidth portions. In some embodiments, two or more of the UL PPDUs 268are transmitted within a same frequency band (e.g., two or more of theUL PPDUs 268 span the same frequency band) using different spatialstreams (e.g., the two or more UL PPDUs 268 are transmitted usingMU-MIMO).

The UL PPDUs 268 correspond to uplink ranging measurement feedbackpackets. The PPDUs 268 respectively include the recorded times t_(1,k)and t_(4,k). In some embodiments, each of one or more PPDUs 268respectively includes (optionally) the recorded angles AoD_(1,k) andAoA_(2,k). In some embodiments, the PPDUs 268 optionally also includerespective channel estimate information determined by the client station154 based on reception of the DL NDP 236.

After receipt of the PPDUs 268, the AP 114 calculates respective oftimes-of-flight between the AP 114 and the client stations 154 using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k), according to anembodiment. Any suitable technique, including currently knowntechniques, may be utilized to calculate a time-of-flight using therecorded times t_(1,k), t_(2,k), t_(3,k), and t_(4,k). Respectivedistances between the AP 114 and the client stations 154 may becalculated using the calculated times-of-flight, e.g., by respectivelymultiplying the times-of-flight by the speed of light, according to anembodiment.

In some embodiments, the AP 114 calculates estimated positions of one ormore of the client stations using the calculated times-of-flight. Forexample, the AP 114 uses triangulation techniques to calculate estimatedpositions of one or more of the client stations using the calculatedtimes-of-flight. In some embodiments, the AP 114 calculates estimatedpositions of one or more of the client stations also using the recordedangles AoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k). For example, therecorded angles AoD_(1,k), AoA_(1,k), AoD_(2,k), and AoA_(2,k) are usedas part of a triangulation algorithm for determining positions ofcommunication devices.

In another embodiment, the order, in time, of the DL FB exchange 210 andthe UL FB exchange 212 is reversed, and the UL FB exchange 212 occursbefore the DL FB exchange 210. In some embodiments, the DL FB exchange210 is omitted. In some embodiments, the UL FB exchange 212 is omitted.

In some embodiments, the AP 114 assigns network identifiers (sometimesreferred to herein as association identifiers (AIDs)) to client stations154 upon the client stations 154 becoming associated with a basicservice set (BSS) managed by the AP 114. For example, if a clientstation 154 requests to become associated with the BSS and the AP 114determines that the client station 154 is permitted to become associatedwith the BSS, the AP 114 will assign an AID to the client station 154and inform the client station 154 of the AID assigned to the clientstation. While the client station 154 is associated with the BSS, the AP114 and the client station 154 use the AID in PPDUs and/or MPDUsexchanged between the AP 114 and associated client station 154. Forexample, when the associated client station 154 participates in the MUranging measurement exchange 200, the AP 114 and the client station 154use the AID in PPDUs and/or MPDUs exchanged during the MU rangingmeasurement exchange 200, such as in one of, or any suitable combinationof two or more of, i) the PPDU 216 and/or the trigger frame within thePPDU 216, ii) one of the UL NDPs 224, iii) the PPDU 228 and/or the NDPannouncement frame within the PPDU 228, iv) the DL NDP 236, v) one ofthe DL FB PPDUs 244 and/or an MPDU within the DL FB PPDU 244, vi) one ofthe UL ACKs 254, vii) the PPDU 260 and/or the trigger frame within thePPDU 260, and viii) one of the UL FB PPDUs 268 and/or an MPDU within theUL FB PPDU 268.

The AP 114, however, sometimes performs a ranging measurement exchangewith one or more client stations 154 that are not associated with theBSS (sometimes referred to as “unassociated client stations”), in someembodiments. Thus, the AP 114 assigns preliminary AIDs (pre-AIDs) to atleast some unassociated client stations 154 prior to the MU rangingmeasurement exchange 200, according to some embodiments. When theunassociated client station 154 participates in the MU rangingmeasurement exchange 200, the AP 114 and the unassociated client station154 use the pre-AID in PPDUs and/or MPDUs exchanged during the MUranging measurement exchange 200, such as in one of, or any suitablecombination of two or more of, i) the PPDU 216 and/or the trigger framewithin the PPDU 216, ii) one of the UL NDPs 224, iii) the PPDU 228and/or the NDP announcement frame within the PPDU 228, iv) the DL NDP236, v) one of the DL FB PPDUs 244 and/or an MPDU within the DL FB PPDU244, vi) one of the UL ACKs 254, vii) the PPDU 260 and/or the triggerframe within the PPDU 260, and viii) one of the UL FB PPDUs 268 and/oran MPDU within the UL FB PPDU 268.

In an embodiment, the AP 114 assigns both i) AIDs to associated clientstations 154 and ii) pre-AIDs to unassociated client stations from asame set of AID values (e.g., the set includes values 1-2007, or anothersuitable range of values), such that no two client stations 154 areassigned a same value of an AID or pre-AID. For example, when a value inthe set is currently assigned as an AID or a pre-AID to a client station154, the AP 114 will not assign the same value to another client station154 as an AID or a pre-AID. In such embodiments, a ranging measurementsession can involve both associated client stations 154 and unassociatedclient stations 154. In an embodiment, a first subset of values in theset is reserved for associated client stations, and the AP 114 assignsAIDs to associated client stations 154 from the first subset; and asecond subset of values (which does not overlap with the first subset)in the set is reserved for unassociated client stations, and the AP 114assigns pre-AIDs to unassociated client stations 154 from the secondsubset.

In another embodiment, the AP 114 is permitted to reuse an AID value fora currently associated client station 154 as a pre-AID for anunassociated client station 154. In such an embodiment, a rangingmeasurement sessions such as described herein are performed separatelyfor association client stations 154 and unassociated client stations154, such that a ranging measurement sessions involves i) onlyassociated client stations 154, or ii) only unassociated client stations154.

In an embodiment, the AP 114 includes the pre-AID in an MPDU one or moreof the DL transmissions illustrated in FIG. 2A. For example, the triggerframe 216 includes a plurality of user information fields (user infofields) corresponding to client stations 154 that are to participate inthe UL MU transmission 220. For instance, one of the user inform fieldsidentifies (e.g., by including the pre-AID in the user info field) thatthe unassociated client station 154 is to transmit an NDP as part of theUL MU transmission 220, according to an embodiment. Additionally, theuser info field that includes the pre-AID also indicates on which one ormore spatial streams the unassociated client station 154 is to transmitan NDP as part of the UL MU transmission 220, according to anembodiment.

In an embodiment, the AP 114 includes the pre-AID in a PHY preamble oneor more of the DL transmissions illustrated in FIG. 2A. For example, thePPDU 260 includes a signal field (e.g., a high efficiency WiFi (HE)signal field B (HE-SIGB), where the HE-SIGB field includes a pluralityof user info fields corresponding to a plurality of client stations 154that are to participate in the MU UL transmission 264, and where eachuser info field includes a respective AID or pre-AID. In an embodiment,the relative positions of the user info fields within the HE-SIGBindicate (in conjunction with other information in the HE-SIGB (e.g.,resource unit (RU) allocation information in a common informationfield)) in which frequency block each client station 154 is to transmitas part of the MU UL transmission 264. Additionally, the user info fieldthat includes the pre-AID also indicates on which one or more spatialstreams the unassociated client station 154 is to transmit as part ofthe UL MU transmission 264, according to an embodiment.

Similarly, as another example, the PPDU 240 includes an HE-SIGB fieldwith a plurality of user info fields corresponding to a plurality ofclient stations 154 that are to participate in the MU UL transmission250, and where each user info field includes a respective AID orpre-AID, according to an embodiment.

FIG. 3 is a timing diagram of an example MU ranging measurementprocedure 300, according to an embodiment. The diagram of FIG. 3 isdescribed in the context of the example network 110 merely forexplanatory purposes. In some embodiments, signals illustrated in FIG. 3are generated by other suitable communication devices in other suitabletypes of wireless networks.

The MU ranging measurement procedure 300 begins at a start time andincludes a plurality of stages 304. In an embodiment, the AP 114performs one or more MU ranging measurement exchanges, and optionallyone or more single-user (SU) ranging measurement exchanges, withdifferent sets of client stations 154 in the stages 304. Each stage 304includes a time slot 308 (sometimes referred to herein as an enhancedfine timing measurement (EFTM) service period (SP)). In an embodiment, afirst time slot 308-1 begins at the start time of the MU rangingmeasurement procedure 300. The time slots 308 occur at an interval.

The AP 114 schedules a set of client stations 154 to participate in oneor more ranging measurement exchanges (e.g., the MU ranging measurementexchange 200 of FIG. 2A or another suitable MU ranging measurementexchange) during each stage 304. If only one client station 154 isscheduled to participate during a particular stage 304, the AP 114 andthe one client station 154 participate in an SU ranging measurementexchange, according to an embodiment.

In an embodiment, within each of one or more of the time slots 308, theAP 114 transmits to client stations 154 one or more packets (sometimesreferred to herein as “scheduling packets”) that indicates which set ofclient stations 154 are to participate in the one or more rangingmeasurement exchanges in the corresponding stage 304. If a clientstation 154 determines, based on receiving the one or more schedulingpackets during a time slot 308, that the client station 154 is not toparticipate in a ranging measurement exchange during the correspondingstage 304, the network interface device 162 of the client station 154 ispermitted to transition to a low power state (sometimes referred toherein as a sleep state) upon an end of the time slot 308, according toan embodiment. For example, the network interface device 162 ispermitted to transition to the low power state at the end of the timeslot 308 and to remain in the low power state until a beginning of thenext time slot 308 in the next stage 304. Prior to a beginning of thenext time slot 308, the network interface device 162 transitions to anactive state so that the network interface device 162 is ready toreceive from the AP 114 within the next time slot 308 the one or morescheduling packets that indicates which set of client stations 154 areto participate in the one or more ranging measurement exchanges in thenext stage 304.

In some embodiments, one or more scheduling packets include one or morepre-AIDs of one or more unassociated client station 154, wherein the AP114 includes a pre-AID in a scheduling packet to indicate to theunassociated client station 154 in which time slot(s) 308 theunassociated client station 154 is to participate in the MU rangingmeasurement exchange 200 of FIG. 2A or another suitable MU rangingmeasurement exchange.

To facilitate an MU ranging measurement procedure such as the MU rangingmeasurement procedure 300 discussed above, the AP 114 communicates tothe client stations 154 an indication of a start time of the MU rangingmeasurement procedure, an indication of an interval of the stages of theMU ranging measurement procedure, and an indication of a duration ofeach time slot, according to some embodiments.

In some embodiments, when the AP 114 assigns a pre-AID to anunassociated client station 154, the pre-AID becomes invalid forunassociated client station 154 after the end of the MU rangingmeasurement procedure 300. Thus, the AP 114 will no longer recognize thepre-AID as corresponding to the unassociated client station 154 afterthe end of the MU ranging measurement procedure 300, according to anembodiment. In some embodiments, the MU ranging measurement procedure300 is ended by the client station 154 terminating the MU rangingmeasurement procedure 300 or the AP 114 terminating the MU rangingmeasurement procedure 300.

In some embodiments, the AP 114 transmits a plurality of SU packets to aplurality of client stations 154 prior to an MU ranging measurementprocedure 300 to provide the plurality of client stations 154 withinformation regarding the MU ranging measurement procedure 300. Forexample, in an embodiment, the AP 114 transmits respective SU packets torespective client stations 154 prior to an MU ranging measurementprocedure 300, where each SU packet includes an indication of the starttime of the MU ranging measurement procedure, an indication of aninterval of the stages of the MU ranging measurement procedure, and anindication of a duration of each time slot. In some embodiments, one ormore of the SU packets also include respective pre-AID(s) assigned toone or more unassociated client stations 154.

FIG. 4 is a timing diagram of an example transmission exchange 400 inwhich the AP 114 transmits a plurality of SU packets to a plurality ofclient stations 154 prior to the MU ranging measurement procedure 300 toprovide the plurality of client stations 154 with information regardingthe MU ranging measurement procedure 300, according to an embodiment.The diagram of FIG. 4 is described in the context of the example network110 merely for explanatory purposes. In some embodiments, signalsillustrated in FIG. 4 are generated by other suitable communicationdevices in other suitable types of wireless networks.

The network interface device 122 of the AP 114 generates a plurality ofpackets 404, each packet 404 corresponding to a respective clientstation 154. Each packet 404 includes an MPDU (e.g., a management frame)having information regarding the MU ranging measurement procedure 300,according to an embodiment. The network interface device 122 of the AP114 transmits each packet 404 as an SU transmission to a respectiveclient station 154, according to an embodiment.

In an embodiment, each packet 404 is transmitted in response to thenetwork interface device 122 of the AP 114 successfully receiving apacket 408 from the corresponding client station 154.

In an embodiment, the packet 408 includes a request frame (sometimesreferred to herein as an “EFTM request frame”) corresponding to an MUranging measurement exchange, such as the example MU ranging measurementexchange 200 of FIG. 2A. In an embodiment, the EFTM request frameincludes an indication that the client station 154 seeks to perform aranging measurement exchange with the AP 114. In some embodiments, theEFTM request frame also includes capability information regarding thetypes of feedback information the client station 154 can provide. Insome embodiment, the AP 114 transmits an ACK frame (not shown) asuitable time period (e.g., SIFS) after an end of reception of thepacket 408 to acknowledge the reception of the packet 408.

In some embodiments in which the packet 408 includes an EFTM requestframe, the packet 404 includes a response frame (sometimes referred toherein as an “EFTM response frame”) corresponding to an MU rangingmeasurement exchange, such as the example MU ranging measurementexchange 200 of FIG. 2A. In an embodiment, the EFTM response frame isresponsive to the EFTM request frame discussed above and indicates thatthe AP 114 will participate in a ranging measurement exchange with theclient station. In an embodiment, the EFTM response frame includesinformation regarding the MU ranging measurement procedure 300 (e.g.,one or more of an indication of a start time of the MU rangingmeasurement procedure 300, an indication of an interval of the stages304 of the MU ranging measurement procedure 300, the indication of theduration of each time slot 308 of the MU ranging measurement procedure300, etc.), according to an embodiment. In some embodiment, the clientstation 154 transmits an ACK frame (not shown) a suitable time period(e.g., SIFS) after an end of reception of the packet 404 to acknowledgethe reception of the packet 404.

In an embodiment, in response to receiving a packet 408 from anunassociated client station 154, the AP 114 assigns a pre-AID to theunassociated client station 154. Additionally, the AP 114 includes theassigned pre-AID in the packet 404 (e.g., in the EFTM request frame) toinform the unassociated client station 154 that the AP 114 has assignedthe pre-AID to the unassociated client station 154 for use during the MUranging measurement procedure 300. In an embodiment, the packet 404includes the pre-AID assigned to the unassociated client station 154.For example, the EFTM response frame in the packet 404 includes thepre-AID assigned to the unassociated client station 154.

FIG. 5A is a diagram of an example information element 500 thatindicates an assignment of a pre-AID to an unassociated client station154, according to an embodiment. The information element 500 is includedin the packet 404 (FIG. 4), according to an embodiment. For example, theinformation element 500 is included in the EFTM response frame in thepacket 404. In other embodiments, the information element 500 isincluded in another suitable packet and/or frame. Similarly, in someembodiments, the EFTM response frame and/or the packet 404 include thepre-AID assigned to the unassociated client station 154 within anothersuitable information element and/or MAC frame different than the exampleinformation element 500.

FIG. 5A illustrates examples number of bits for various fields of theinformation element 500 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 5A illustrates an example arrangement of fields within theinformation element 500 merely for illustrative purposes. In otherembodiments, the fields of the information element 500 are arranged indifferent suitable manners. In some embodiments, one or more of thefields illustrated in FIG. 5A are omitted, and/or additional fields areincluded in the information element.

The information element 500 includes an element identifier (ID) field504 and an element ID extension field 508 that includes respectivevalues that identify the information element 500 as being an informationelement that indicates an assignment of a pre-AID to a client station154 (e.g., to an unassociated client station 154). In an embodiment, awireless communication protocol specifies a plurality of differentinformation elements, and the element ID field 504 and optionally theelement ID extension field 508 indicate a particular information elementamong the plurality of different information elements. In an embodiment,different information elements have respective formats, and therespective values of the element ID field 504 and the element IDextension field 508 thus indicate that the information element 500 hasthe format illustrated in FIG. 5A (or another suitable format). In someembodiments, the element ID extension field 508 is omitted, and thevalue of the element ID field 504 identifies the information element 500as being an information element that indicates an assignment of apre-AID to a client station 154 (e.g., to an unassociated client station154), and that the information element 500 has the format illustrated inFIG. 5A (with the element ID extension field 508 omitted).

The information element 500 also includes a length field 512, whichindicates a length of the information element 500. In anotherembodiment, the length field 512 is omitted. For example, the length ofthe information element 500 is defined by the wireless communicationprotocol, and thus a communication device that receives the informationelement 500 determines the length of the information element 500 basedon the value(s) of the element ID field 504 and optionally the elementID extension field 508, according to an embodiment.

The information element 500 further includes a pre-AID field 516 thatincludes a value of the pre-AID being assigned to the client station 154(e.g., to an unassociated client station 154). In an embodiment, theinformation element 500 is included in a unicast MAC data unit (e.g., aunicast EFTM response frame, a unicast MPDU, or another suitable unicastMAC data unit), where the MAC data unit includes a unicast MAC addressof the client station 154 (e.g., in a destination address field in a MACheader of the MAC data unit) to which the pre-AID is being assigned, andthus the client station 154 determines, based on the information elementbeing in a unicast MAC data unit having a MAC address of the clientstation 154, that the pre-AID in the pre-AID field 516 is being assignedto the client station 154.

FIG. 5B is a diagram of another example information element 550 thatindicates an assignment of a pre-AID to an unassociated client station154, according to an embodiment. The information element 550 is includedin the packet 404 (FIG. 4), according to an embodiment. For example, theinformation element 550 is included in the EFTM response frame in thepacket 404. In other embodiments, the information element 550 isincluded in another suitable packet and/or frame. Similarly, in someembodiments, the EFTM response frame and/or the packet 404 include thepre-AID assigned to the unassociated client station 154 within anothersuitable information element and/or MAC frame different than the exampleinformation element 550.

FIG. 5B illustrates examples number of bits for various fields of theinformation element 550 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 5B illustrates an example arrangement of fields within theinformation element 550 merely for illustrative purposes. In otherembodiments, the fields of the information element 550 are arranged indifferent suitable manners. In some embodiments, one or more of thefields illustrated in FIG. 5B are omitted, and/or additional fields areincluded in the information element.

The information element 550 is similar to the information element 500 ofFIG. 5A, and like-numbered elements are not described in detail forpurposes of brevity.

The information element 550 includes an address present field 554 whichindicates whether the information element 550 includes a MAC addressfield 560. For example, when the information element 550 is included ina unicast MAC data unit, the MAC address field 560 is omitted and theaddress present field 554 is set to a value to indicate that the MACaddress field 560 is not included in the information element 550. Insome embodiments, when the information element 550 is included in abroadcast packet (e.g., the packet includes a MAC data unit with adestination address in a MAC header set to a broadcast address), or in agroup-addressed packet (e.g., the packet includes a MAC data unit with adestination address in a MAC header set to a multicast address whichcorresponds to a group of multiple communication devices), the MACaddress field 560 is included in the information element 550 and theaddress present field 554 is set to a value to indicate that the MACaddress field 560 is included.

In an embodiment, when the information element 550 includes the MACaddress field 560, an unassociated client station 154 receiving theinformation element 550 determines, based on whether the MAC address inthe field 560 is the MAC address of the unassociated client station 154,whether the pre-AID in the pre-AID field 516 is being assigned to theunassociated client station 154. If the unassociated client station 154determines that the MAC address in the field 560 is the MAC address ofthe unassociated client station 154, then the unassociated clientstation 154 determines that the pre-AID in the pre-AID field 516 isbeing assigned to the unassociated client station 154.

In some embodiments, the information element 500 and/or the informationelement 550 includes a field (not shown) that indicates an end time atwhich the pre-AID is no longer valid for the unassociated client station154. In some embodiments, the information element 500 and/or theinformation element 550 includes a field (not shown) that indicates astart time at which the pre-AID becomes valid for the unassociatedclient station 154.

FIG. 6 is a timing diagram of an example transmission exchange 600 inwhich the AP 114 performs an MU transmission a plurality client stations154 prior to the MU ranging measurement procedure 300 that provides oneor more unassociated client stations 154, among the plurality of clientstations 154, with one or more respective pre-AIDs assigned to the oneor more unassociated client stations 154 for use during the MU rangingmeasurement procedure 300, according to an embodiment. The diagram ofFIG. 6 is described in the context of the example network 110 merely forexplanatory purposes. In some embodiments, signals illustrated in FIG. 6are generated by other suitable communication devices in other suitabletypes of wireless networks.

The network interface device 122 of the AP 114 generates a downlink (DL)PPDU 604 having a trigger frame configured to prompt a plurality ofclient stations 154 to transmit as part of an uplink (UL) MUtransmission 608 (e.g., an UL orthogonal frequency division multipleaccess (OFDMA) transmission and/or an ULMU-multiple-input-multiple-output (MU-MIMO) transmission). In anembodiment, the trigger frame in the DL PPDU 604 includes informationthat prompts client stations 154 that want to participate in a rangingmeasurement procedure to provide, in the UL MU transmission 608,requests to participate in the ranging measurement procedure. Thenetwork interface device 122 of the AP 114 then transmits the DL PPDU604.

In an embodiment, the AP 114 (e.g., the network interface device 122)allocates resource units (RUs) (e.g., blocks of OFDM tones) forunassociated client stations 154 to participate in the UL MUtransmission 608 via contention-based OFDMA transmissions, and thenetwork interface device 122 includes in the trigger frame in the DLPPDU 504 an indication that particular RUs have been allocated forcontention-based OFDMA transmissions. For example, the network interfacedevice 122 allocates one or blocks of one or more RUs, and includes in acommon information field of the trigger frame an indication of theallocated one or more blocks of RU(s). Additionally, the networkinterface device 122 includes, for each allocated block of RU(s), a userinformation field having an AID field that indicates an AID to which theblock of RU(s) has been allocated. For each block of RU(s) allocated foruse by unassociated client stations 154, the network interface device122 includes in the AID field of the corresponding user informationfield a reserved AID value, where the reserved AID value indicates theblock of RU(s) is reserved for contention-based OFDMA transmissions. Inan embodiment, the reserved AID value indicates the block of RU(s) isreserved for contention-based OFDMA transmissions by unassociated clientstation 154. In some embodiments, the AP 114 (e.g., the networkinterface device 122) generates the trigger frame in the DL PPDU 504 andthe unassociated client stations 154 participate in the UL MUtransmission 608 according to random access OFDMA technique such asdescribed in draft 2.2 of the IEEE 802.11ax Standard, dated February2018.

In an embodiment, the trigger frame in the DL PPDU 604 includesinformation that indicates the trigger frame in the DL PPDU 604 issoliciting requests to participate in a ranging measurement procedure.In an embodiment, the trigger frame includes a trigger type subfieldhaving information indicating that the trigger frame 604 is a type oftrigger frame specifically for soliciting requests to participate in aranging measurement procedure, such as the MU ranging measurementexchange 200, and/or the ranging measurement procedure 300. In anembodiment, the value of the trigger type subfield is selected fromamong a plurality of values corresponding to a plurality of triggervariants defined by a communication protocol (e.g., the IEEE 802.11Standard). Different trigger variants correspond to different type ofinformation being solicited in an UL MU transmission and/or the UL MUtransmission being part of different types of procedures, in someembodiments. In an illustrative embodiment, the plurality of triggervariants defined by the communication protocol include any suitablecombination of two or more of the following: i) a basic trigger forsoliciting an UL MU transmission having basic user data fromcommunication devices, ii) a beamforming report poll trigger forsoliciting an UL MU transmission having beamforming training feedbackfrom communication devices, iii) an MU request-to-send trigger forsoliciting an UL MU transmission having clear-to-send (CTS) frames fromcommunication devices, iv) a buffer status report poll (BSRP) triggerfor soliciting an UL MU transmission having information regarding howmuch user data communication devices have to send to the AP 114, v) atrigger for soliciting requests to participate in a ranging measurementprocedure, etc.

In another embodiment, the trigger frame in the DL PPDU 604 includes acommon information field, with a subfield having information thatindicates the trigger frame in the DL PPDU 604 is soliciting requests toparticipate in a ranging measurement procedure.

In response to the DL PPDU 604, a plurality of client stations 154simultaneously transmit as part of the UL MU transmission 608 (e.g., anUL OFDMA transmission and/or an UL MU-MIMO transmission). The UL MUtransmission 608 includes requests by client stations 154 to participatein a ranging measurement procedure. The network interface device 122 ofthe AP 114 analyzes the requests to participate in the rangingmeasurement procedure.

In an embodiment, one or more unassociated client stations 154 transmitsrequests to participate in a ranging measurement procedure in RU(s)allocated by the AP 114 for contention-based OFDMA transmissions as partof the UL MU transmission 608. For example, unassociated client stations154 randomly or pseudorandomly select RUs that have been allocated bythe AP 114 for contention-based transmissions, and then transmitrequests via the selected RUs as part of the UL MU transmission 608. Ifmultiple unassociated client stations 154 select the same RU and thustransmit requests within the same RU, a collision will result and the AP114 likely will not correctly receive any of transmissions of theunassociated client stations 154 transmitted via the same RU.

The network interface device 122 of the AP 114 processes the UL MUtransmission 608 to determine which client station 154 are requesting toparticipate in a ranging measurement procedure. For requests toparticipate received from unassociated client stations 154, the networkinterface device 122 assigns respective pre-AIDs to the unassociatedclient stations 154.

In an embodiment, the network interface device 122 of the AP 114generates a DL SU PPDU 612 that includes a broadcast frame withinformation corresponding to an MU ranging measurement procedure, suchas the example MU ranging measurement procedure 300 of FIG. 3. Forexample, in an embodiment, the information corresponding to the MUranging measurement procedure includes an indication of a start time ofthe MU ranging measurement procedure 300, an indication of an intervalof the stages of the MU ranging measurement procedure 300, and anindication of the duration of each time slot 308 of the MU rangingmeasurement procedure 300.

Additionally, the information corresponding to an MU ranging measurementprocedure also includes pre-AIDs assigned to respective unassociatedclient stations 154. Upon receiving the DL SU PPDU 612, at least someunassociated client stations 154 (e.g., unassociated client stations 154whose requests in the UL MU 608 transmission were correctly received bythe AP 114) process the DL SU PPDU 612 to determine informationregarding an upcoming MU ranging measurement procedure, includingrespective pre-AIDs assigned to the unassociated client stations 154 forthe upcoming MU ranging measurement procedure.

In some embodiments, the network interface device 122 of the AP 114generates and transmits a DL MU PPDU instead of the DL SU PPDU 612,wherein the DL MU PPDU includes the information corresponding to the MUranging measurement procedure discussed above.

FIG. 7 is a diagram of an example request frame 700 (sometimes referredto herein as an “EFTM request frame”) that client stations 154 transmitas part of the UL MU transmission 608, according to an embodiment. Inother embodiments, the request frame 700 is included in another suitablesingle-user or multi-user transmission.

FIG. 7 illustrates examples number of octets for various fields of therequest frame 700 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 7 illustrates an example arrangement of fields within the requestframe 700 merely for illustrative purposes. In other embodiments, thefields of the request frame 700 are arranged in different suitablemanners. In some embodiments, one or more of the fields illustrated inFIG. 7 are omitted, and/or additional fields are included in the requestframe.

The request frame 700 includes a frame control field 704 set to a valueto indicate that the frame 700 corresponds to a request to participatein a ranging measurement procedure.

The request frame 700 also includes a plurality of address fields 708,where one of the address fields 708 indicates a MAC address of the AP114 (e.g., a receiver address) and another one of the address fields 708indicates a MAC address of the client station 154 (e.g., a transmitteraddress) that is transmitting the request frame 700.

The request frame 700 also includes a frame body 720. The frame body 720includes a plurality of fields, including a field 744 that includesinformation regarding ranging measurement procedures. For example, thefield 744 includes capability information regarding capabilities of theclient station 154 with respect to participating in a rangingmeasurement procedure, according to an embodiment.

FIG. 8A is a diagram of an example response frame 800 (sometimesreferred to herein as an “EFTM response frame”) that the AP 114transmits as part of the DL SU transmission 612, according to anembodiment. In other embodiments, the response frame 800 is included inanother suitable single-user or multi-user transmission.

FIG. 8A illustrates examples number of octets for various fields of theresponse frame 800 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 8A illustrates an example arrangement of fields within the responseframe 800 merely for illustrative purposes. In other embodiments, thefields of the response frame 800 are arranged in different suitablemanners. In some embodiments, one or more of the fields illustrated inFIG. 8A are omitted, and/or additional fields are included in theresponse frame.

The response frame 800 includes a frame control field 804 set to a valueto indicate that the frame 800 corresponds to a response to one or morerequests to participate in a ranging measurement procedure.

The response frame 800 also includes a plurality of address fields 808,where one of the address fields 808 indicates a broadcast MAC address(e.g., a receiver address) and another one of the address fields 808indicates a MAC address of the AP 114 (e.g., a transmitter address),which is transmitting the response frame 800.

The response frame 800 also includes a frame body 820. The frame body820 includes a plurality of fields, including a field 844 that includesinformation regarding an upcoming ranging measurement procedure. Forexample, in an embodiment, the field 844 includes capability informationregarding capabilities of the AP 114 with respect to participating in aranging measurement procedure. The frame body 820 includes a field 848,which includes timing information regarding an upcoming rangingmeasurement procedure. For example, in an embodiment, the timinginformation regarding the ranging measurement procedure includes anindication of a start time of the MU ranging measurement procedure 300,an indication of an interval of the stages of the MU ranging measurementprocedure 300, and an indication of the duration of each time slot 308of the MU ranging measurement procedure 300.

Additionally, the field 848 includes information indicating anassignment of one or more pre-AIDs to one or more respectiveunassociated client stations 154 for the upcoming ranging measurementprocedure.

FIG. 8B is a diagram of an example format of an information element 850that is included in the field 848, according to an embodiment. Theinformation element 850 indicates an assignment of a pre-AID to anunassociated client station 154 and also provides timing informationregarding an upcoming ranging measurement procedure, according to anembodiment. In an embodiment, a respective information element 850 isincluded in the field 848 (FIG. 8A) for multiple unassociated clientstations 154, according to an embodiment. In other embodiments, theinformation element 850 is included in another suitable packet, frame,and/or field.

FIG. 8B illustrates examples number of bits for various fields of theinformation element 850 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 8B illustrates an example arrangement of fields within theinformation element 850 merely for illustrative purposes. In otherembodiments, the fields of the information element 850 are arranged indifferent suitable manners. In some embodiments, one or more of thefields illustrated in FIG. 8B are omitted, and/or additional fields areincluded in the information element.

The information element 850 includes an element ID field 854 and anelement ID extension field 858 that includes respective values thatidentify the information element 850 as being an information elementthat indicates an assignment of a pre-AID to a client station 154 (e.g.,to an unassociated client station 154) and also indicates timinginformation regarding an upcoming ranging measurement procedure. In anembodiment, a wireless communication protocol specifies a plurality ofdifferent information elements, and the element ID field 854 andoptionally the element ID extension field 858 indicate a particularinformation element among the plurality of different informationelements. In an embodiment, different information elements haverespective formats, and the respective values of the element ID field854 and the element ID extension field 858 thus indicate that theinformation element 850 has the format illustrated in FIG. 8B (oranother suitable format). In some embodiments, the element ID extensionfield 858 is omitted, and the value of the element ID field 854identifies the information element 850 as being an information elementthat indicates an assignment of a pre-AID to a client station 154 (e.g.,to an unassociated client station 154) and also indicates timinginformation regarding an upcoming ranging measurement procedure, andthat the information element 850 has the format illustrated in FIG. 8B(with the element ID extension field 858 omitted).

The information element 850 also includes a length field 862, whichindicates a length of the information element 850. In anotherembodiment, the length field 862 is omitted. For example, the length ofthe information element 850 is defined by the wireless communicationprotocol, and thus a communication device that receives the informationelement 858 determines the length of the information element 858 basedon the value(s) of the element ID field 854 and optionally the elementID extension field 858, according to an embodiment.

The information element 850 further includes a pre-AID field 866 thatincludes a value of the pre-AID being assigned to the client station 154(e.g., to an unassociated client station 154). In an embodiment, theinformation element 850 is included in a broadcast MAC data unit (e.g.,a broadcast EFTM response frame, a broadcast MPDU, or another suitablebroadcast MAC data unit), where the MAC data unit includes a broadcastMAC address (e.g., in a destination address field in a MAC header of theMAC data unit). In an embodiment, the information element 850 isincluded in a multicast MAC data unit (e.g., a multicast EFTM responseframe, a multicast MPDU, or another suitable multicast MAC data unit),where the MAC data unit includes a multicast MAC address (e.g., in adestination address field in a MAC header of the MAC data unit) thatcorresponds to a group of multiple client stations 154. The informationelement 850 also includes a MAC address field 870 that includes a MACaddress of the unassigned client station to which the informationelement 850 is intended, and the unassigned client station 154determines, based on the MAC address field 870 having a MAC address ofthe client station 154, that the pre-AID in the pre-AID field 866 isbeing assigned to the client station 154.

The information element 850 also includes a field 874 that includes anindication of a start time of the MU ranging measurement procedure(e.g., the MU ranging measurement procedure 300), according to anembodiment. The information element 850 also includes a field 878 thatincludes an indication of an interval of the stages of the MU rangingmeasurement procedure (e.g., the interval of the stages 304). Theinformation element 850 also includes a field 882 that includes anindication of a duration of each time slot (e.g., the times slots 308),according to some embodiments.

Referring again to FIGS. 6 and 8A, in some embodiments, the DL SU PPDU612 includes a plurality of unicast EFTM frames addressed to respectiveclient stations. For example, the plurality of unicast EFTM frames areincluded in an aggregate MPDU (A-MPDU) within the DL SU PPDU 612. Thus,in some embodiments, a plurality of unicast frames similar to the frame800 are included in the DL SU PPDU 612, where each frame 800 includes adestination address 808 set to a unicast MAC address of a respectiveclient station 154. In such embodiments, each frame 800 includes oneinformation element 850, and the MAC address 870 is omitted from theinformation element 850, in an embodiment.

FIG. 8C is a diagram of fields within the frame body 820 (FIG. 8A),according to another embodiment. FIG. 8C illustrates examples number ofoctets for various fields in the frame body 820 merely for illustrativepurposes. In other embodiments, one or more fields have differentsuitable numbers of octets. FIG. 8C illustrates an example arrangementof fields within the frame body 820 merely for illustrative purposes. Inother embodiments, the fields within the frame body 820 are arranged indifferent suitable manners. In some embodiments, one or more of thefields illustrated in FIG. 8C are omitted, and/or additional fields areincluded in the frame body 820.

The contents 880 of the frame body 820 are similar to the frame bodyformat illustrated in FIG. 8A, and like-numbered elements are notdescribed in detail merely for purposes of brevity. The contents 880include a plurality of fields, including a field 884, which includestiming information regarding an upcoming ranging measurement procedure.For example, in an embodiment, the timing information regarding theranging measurement procedure includes an indication of a start time ofthe MU ranging measurement procedure 300, an indication of an intervalof the stages of the MU ranging measurement procedure 300, and anindication of the duration of each time slot 308 of the MU rangingmeasurement procedure 300.

Additionally, the contents 880 include a separate field 888 havinginformation indicating an assignment of one or more pre-AIDs to one ormore respective unassociated client stations 154 for the upcomingranging measurement procedure. In an embodiment, the field 888 includesan information element similar to the example information element 850discussed above with respect claims 8A and 8B, but that omits the fields874, 878, and 882.

FIG. 9 is a timing diagram of another example transmission exchange 900in which the AP 114 performs an MU transmission a plurality clientstations 154 prior to the MU ranging measurement procedure 300 thatprovides one or more unassociated client stations 154, among theplurality of client stations 154, with one or more respective pre-AIDsassigned to the one or more unassociated client stations 154 for useduring the MU ranging measurement procedure 300, according to anembodiment. The diagram of FIG. 9 is described in the context of theexample network 110 merely for explanatory purposes. In someembodiments, signals illustrated in FIG. 9 are generated by othersuitable communication devices in other suitable types of wirelessnetworks.

The diagram of FIG. 9 is similar to the diagram of FIG. 6, andlike-numbered elements are not described in detail merely for purposesof brevity.

The network interface device 122 of the AP 114 processes the UL MUtransmission 608 to determine which client station 154 are requesting toparticipate in a ranging measurement procedure. For requests toparticipate received from unassociated client stations 154, the networkinterface device 122 assigns respective pre-AIDs to the unassociatedclient stations 154.

In an embodiment, the network interface device 122 of the AP 114generates a DL MU PPDU 904 that includes information acknowledgingreceipt of requests in the UL MU transmission 608 that were correctlyreceived by the network interface device 122. In an embodiment, the DLMU PPDU 904 is generated to include a multi-station block acknowledgment(M-BA) frame that acknowledges receipt of requests in the UL MUtransmission 608 that were correctly received by the network interfacedevice 122.

In an embodiment, the M-BA frame in the DL MU PPDU 904 also includespre-AIDs assigned to respective unassociated client stations 154. Uponreceiving the DL MU PPDU 904, at least some unassociated client stations154 (e.g., unassociated client stations 154 whose requests in the UL MU608 transmission were correctly received by the AP 114) process the DLMU PPDU 904 to determine the respective pre-AIDs assigned to theunassociated client stations 154 for the upcoming MU ranging measurementprocedure.

The network interface device 122 of the AP 114 then generates a DL MUPPDU 908 that includes information corresponding to an MU rangingmeasurement procedure, such as the example MU ranging measurementprocedure 300 of FIG. 3. For example, in an embodiment, the informationcorresponding to the MU ranging measurement procedure includes anindication of a start time of the MU ranging measurement procedure 300,an indication of an interval of the stages of the MU ranging measurementprocedure 300, and an indication of the duration of each time slot 308of the MU ranging measurement procedure 300. In an embodiment, the DL MUPPDU 908 includes respective EFTM response frames for multiple clientstations 154, where the EFTM response frames corresponding tounassociated client stations 154 include the corresponding pre-AIDs.

The multiple client stations 154 transmit respective acknowledgments inan UL MU transmission 912, wherein the respective acknowledgmentsacknowledge the EFTM responses in the DL MU transmission 908.

Additionally, the information corresponding to an MU ranging measurementprocedure also includes pre-AIDs assigned to respective unassociatedclient stations 154. Upon receiving the DL SU PPDU 612, at least someunassociated client stations 154 (e.g., unassociated client stations 154whose requests in the UL MU 608 transmission were correctly received bythe AP 114) process the DL SU PPDU 612 to determine informationregarding an upcoming MU ranging measurement procedure, includingrespective pre-AIDs assigned to the unassociated client stations 154 forthe upcoming MU ranging measurement procedure.

Referring now to FIGS. 6 and 9, in other embodiments, unassociatedclient stations 154 randomly or pseudo-randomly select pre-AIDs from aset of AIDs reserved for use as pre-AIDs (e.g., the AP 114 will notassign AIDs for associated stations from the set of AIDs reserved foruse as pre-AIDs). Thus, in some embodiments, the AP 114 does not assignpre-AIDs to unassociated client stations 154 and does not communicateassigned pre-AIDs to client stations such as described above. Ifmultiple unassociated client stations 154 choose the same pre-AID, theAP 114 does not acknowledge EFTM requests from such client station 154.In such scenarios, an unassociated client station 154 randomly orpseudo-randomly chooses another pre-AID from the set of AIDs reservedfor use as pre-AIDs and transmits another EFTM request to the AP 114 ata later time.

FIG. 10 is a timing diagram of an example ranging measurement setupprocedure 1000 prior to an MU ranging measurement procedure, accordingto an embodiment. FIG. 10 is described in the context of the examplenetwork 110 merely for explanatory purposes. In some embodiments,signals illustrated in FIG. 10 are generated by other suitablecommunication devices in other suitable types of wireless networks.

During a first frame exchange 1004, a first communication device (e.g.,the AP 114) transmits a DL PPDU 1008 having a trigger frame to promptmultiple second communication devices (e.g., client stations 154) tosimultaneously transmit NDP feedbacks 1012 as part of an UL OFDMA NDPtransmission 1016, where each client station uses several differenttones in the UL OFDMA NDP transmission 1016 to send a respective requestindication. In an embodiment, the trigger frame 1008 is a type oftrigger frame specifically for prompting UL OFDMA NDP transmissions fromunassociated client stations 154 (e.g., a trigger type field in thetrigger frame 1008 is set to a particular value that corresponds toprompting UL OFDMA NDP transmissions from unassociated client stations154). In an embodiment, the trigger frame 1008 is a type of triggerframe specifically for prompting UL OFDMA NDP transmissions fromunassociated client stations 154 that want to participate in a rangingmeasurement procedure (e.g., a trigger type field in the trigger frame1008 is set to a particular value that corresponds to prompting UL OFDMANDP transmissions from unassociated client stations 154 that want toparticipate in a ranging measurement procedure).

In an embodiment, the trigger frame 1008 includes a starting value ofpre-AIDs to be assigned (pre-AID_start), and indices (e.g., x_(i)=0, 1,2, . . . ) of RUs that unassociated client stations 154 can use totransmit NDPs responsive to the trigger frame 1008. Thus, each RU_(i)corresponds to a particular pre-AID (e.g., pre-AID_start+x_(i)). Eachunassociated client station 154 randomly or pseudo-randomly chooses anRU in which to transmit an NDP 1012 as part of the UL OFDMA transmission1016, and thus also chooses a pre-AID for the unassociated clientstation 154. In some scenarios multiple unassociated client stations 154choose a same RU.

In some embodiments, the trigger frame in the DL PPDU 1008 is configuredto prompt an UL MU transmission similar to an UL MU transmissionaccording to the NDP feedback report procedure described in draft 2.2 ofthe IEEE 802.11ax Standard, dated February 2018.

The trigger frame 1008 prompts multiple unassociated client stations 154to begin simultaneously transmitting NDPs 1012 as part of the UL MUtransmission 1016 a defined time period after an end of the PPDU 1008.In an embodiment, the defined time period is the short interframe space(SIFS) defined by the IEEE 802.11 Standard. In other embodiments,another suitable time period is utilized. In some embodiments, the AP114 (e.g., the network interface device 122) generates the trigger framein the DL PPDU 1008 and the unassociated client stations 154 participatein the UL MU transmission 1016 according to a random access OFDMAtechnique such as described in draft 2.2 of the IEEE 802.11ax Standard,dated February 2018.

Each received NDP 1012 indicates to the AP 114 that a correspondingunassociated client station 154 may want to participate in a rangingmeasurement procedure. At this point in the procedure 1000, the AP 114does not yet know the identities (e.g., the MAC addresses) of theunassociated client stations 154 that participated in the UL MUtransmission 1016.

Responsive to the UL OFDMA transmission 1016, the AP 114 beginstransmitting an acknowledgment transmission 1020 a defined time periodafter an end of the UL OFDMA transmission 1016. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized.

In some embodiments, the acknowledgment transmission 1020 includes anM-BA frame. For example, in an embodiment, the acknowledgmenttransmission 1020 includes an M-BA frame that acknowledges multiple NDPs1012 and that is transmitted across a same set of frequency bandwidthportions as the multiple NDPs 1012. In an embodiment, the M-BA frameacknowledges receipt of multiple NDPs 1012 using the pre-AIDs thatcorrespond to the RUs in which NDPs 1012 were correctly received.

During an EFTM request exchange 1030, the AP 114 (e.g., the networkinterface device 122) generates and transmits a DL PPDU 1034 having atrigger frame to prompt multiple the unassociated client stations 154(for which NDPs 1012 were correctly received) to simultaneously transmitEFTM request frames 1038 as part of an UL OFDMA transmission 1042. In anembodiment, the AP 114 (e.g., the network interface device 122)generates the trigger frame 1034 to include the pre-AIDs determined bythe AP 114 (e.g., the network interface device 122) based on thecorrectly received NDPs 1012.

In some scenarios multiple unassociated client stations 154 transmitEFTM requests within a same RU, which causes a collision and which causethe AP 114 to typically not correctly receive an EFTM request from anyof the multiple unassociated client stations 154 transmitting within thesame RU.

Based on the UL OFDMA transmission 1042, the AP 114 (e.g., the networkinterface device 122) determines the identities (e.g., the MACaddresses) of unassociated client stations 154 that participated in theUL OFDMA transmission 1042 and for which the AP 114 correctly receivedEFTM requests 1038. For example, the EFTM request frames 1038 includerespective MAC addresses of the unassociated client stations 154.Responsive to the UL OFDMA transmission 1042, the AP 114 beginstransmitting an acknowledgment transmission 1046 a defined time periodafter an end of the UL OFDMA transmission 1042. In an embodiment, thedefined time period is SIFS. In other embodiments, another suitable timeperiod is utilized.

In some embodiments, the acknowledgment transmission 1046 includes anM-BA frame. For example, in an embodiment, the acknowledgmenttransmission 1046 includes an M-BA frame that acknowledges multiple EFTMrequest frames 1038. In an embodiment, the M-BA frame acknowledgesreceipt of multiple NDPs 1012 using the pre-AIDs that correspond to theRUs in which EFTM request frames 1038 were correctly received and/orusing MAC addresses of the unassociated client stations 154 (e.g.,determined from the correctly received EFTM request frames 1038).

In an exchange 1050, the network interface device 122 generates andtransmits an MU transmission 1054 that includes respective EFTM responseframes 1058 corresponding to an MU ranging measurement exchange, such asthe example MU ranging measurement procedure 300 of FIG. 3. In anembodiment, each EFTM response frame 1058 is responsive to acorresponding correctly received EFTM request frame 1038, and indicatesthat the AP 114 will participate in a ranging measurement exchange withthe client station. In an embodiment, the EFTM response frame 1058includes information regarding the MU ranging measurement procedure 300(e.g., one or more of an indication of a start time of the MU rangingmeasurement procedure 300, an indication of an interval of the stages304 of the MU ranging measurement procedure 300, the indication of theduration of each time slot 308 of the MU ranging measurement procedure300, etc.), according to an embodiment.

Responsive to the MU transmission 1054, the unassociated client stations154 transmit an UL MU transmission 1062 that includes, e.g., an M-BAframe that acknowledges receipt of the EFTM response frames 1058 by theunassociated client stations 154.

In an embodiment, the EFTM request frame 1038 has a format the same asor similar to the EFTM request frame 700 of FIG. 7.

FIG. 11A is a diagram an example response frame 1100 (sometimes referredto herein as an “EFTM response frame”) that the AP 114 transmits as partof the DL MU transmission 1054, according to an embodiment. In otherembodiments, the response frame 1100 is included in another suitablesingle-user or multi-user transmission.

FIG. 11A illustrates examples number of octets for various fields of theresponse frame 1100 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 11A illustrates an example arrangement of fields within theresponse frame 1100 merely for illustrative purposes. In otherembodiments, the fields of the response frame 1100 are arranged indifferent suitable manners. In some embodiments, one or more of thefields illustrated in FIG. 11A are omitted, and/or additional fields areincluded in the response frame.

The response frame 1100 is similar to the response frame 800 of FIG. 8A,and like-numbered elements are not described in detail merely forpurposes of brevity.

The response frame 1100 includes a frame control field 1104 set to avalue to indicate that the frame 100 corresponds to a response to one ormore requests to participate in a ranging measurement procedure.

The response frame 1100 also includes a frame body 1108. The frame body1108 includes a plurality of fields, including a field 1120, whichincludes timing information regarding an upcoming ranging measurementprocedure. For example, in an embodiment, the timing informationregarding the ranging measurement procedure includes an indication of astart time of the MU ranging measurement procedure 300, an indication ofan interval of the stages of the MU ranging measurement procedure 300,and an indication of the duration of each time slot 308 of the MUranging measurement procedure 300.

FIG. 11B is a diagram of an example format of an information element1150 that is included in the field 1120, according to an embodiment. Theinformation element 1150 provides timing information regarding anupcoming ranging measurement procedure, according to an embodiment.

FIG. 11B illustrates examples number of bits for various fields of theinformation element 1150 merely for illustrative purposes. In otherembodiments, one or more fields have different suitable numbers of bits.FIG. 11B illustrates an example arrangement of fields within theinformation element 1150 merely for illustrative purposes. In otherembodiments, the fields of the information element 1150 are arranged indifferent suitable manners. In some embodiments, one or more of thefields illustrated in FIG. 11B are omitted, and/or additional fields areincluded in the information element.

The information element 1150 includes an element ID field 1154 and anelement ID extension field 1158 that includes respective values thatidentify the information element 1150 as being an information elementthat indicates timing information regarding an upcoming rangingmeasurement procedure. In an embodiment, a wireless communicationprotocol specifies a plurality of different information elements, andthe element ID field 1154 and optionally the element ID extension field1158 indicate a particular information element among the plurality ofdifferent information elements. In an embodiment, different informationelements have respective formats, and the respective values of theelement ID field 1154 and the element ID extension field 1158 thusindicate that the information element 1150 has the format illustrated inFIG. 11B (or another suitable format). In some embodiments, the elementID extension field 1158 is omitted, and the value of the element IDfield 154 identifies the information element 1150 as being aninformation element that indicates timing information regarding anupcoming ranging measurement procedure, and that the information element1150 has the format illustrated in FIG. 11B (with the element IDextension field 1158 omitted).

The information element 1150 also includes a length field 1162, whichindicates a length of the information element 1150. In anotherembodiment, the length field 1162 is omitted. For example, the length ofthe information element 1150 is defined by the wireless communicationprotocol, and thus a communication device that receives the informationelement 1150 determines the length of the information element 1150 basedon the value(s) of the element ID field 154 and optionally the elementID extension field 1158, according to an embodiment.

The information element 1150 also includes a field 1174 that includes anindication of a start time of the MU ranging measurement procedure(e.g., the MU ranging measurement procedure 300), according to anembodiment. The information element 1150 also includes a field 1178 thatincludes an indication of an interval of the stages of the MU rangingmeasurement procedure (e.g., the interval of the stages 304). Theinformation element 1150 also includes a field 1182 that includes anindication of a duration of each time slot (e.g., the times slots 308),according to some embodiments.

In some embodiments, the timing information field 884 (FIG. 8C) includesan information element the same as or similar to the information element1150 of FIG. 11B.

In some embodiments, the timing information field 748 of the requestframe 700 (FIG. 7) and/or the timing information field 1120 of therequest frame 1100 (FIG. 11A) include an information element the same asor similar to the information element 1150 of FIG. 11B. For example, inan EFTM request frame, the field 1174 includes an indication of arequested start time of an MU ranging measurement procedure, the field1178 includes an indication of a requested interval of the stages of theMU ranging measurement procedure (e.g., the interval of the stages 304),and the field 1182 includes an indication of a requested duration ofeach time slot (e.g., the times slots 308), according to someembodiments.

FIG. 12 is a flow diagram of an example method 1200 for performing aranging measurement procedure, according to an embodiment. In someembodiments, the network interface device 122 of FIG. 1 is configured toimplement the method 1200. The method 1200 is described, however, in thecontext of the network interface device 122 merely for explanatorypurposes and, in other embodiments, the method 1200 is implemented byanother suitable device. For instance, in an embodiment, the networkinterface device 162 of FIG. 1, or another suitable WLAN networkinterface device is configured to implement the method 1200.

The method 1200 is implemented in conjunction with the procedures, frameformats, information element formats, etc., described above inconnection with one or more of FIGS. 2A, 2B, 3, 5A, 5B, 6, 7, 8A-C, and9, in various embodiments. In other embodiments, the method 1200 isimplemented in conjunction with suitable procedures, frame formats,information element formats, etc., different that those discussed abovein connection with FIGS. 2A, 2B, 3, 5A, 5B, 6, 7, 8A-C, and 9.

At block 1204, the AP 114 determines (e.g., the network interface device122 determines, the MAC processor 126 determines, etc.) that anunassociated client station 154 requests to participate in a rangingmeasurement procedure with the AP device. The unassociated clientstation 154 is not currently associated with a wireless communicationnetwork managed by the AP 114 (e.g., a BSS) and has not been assigned,by the AP 114, a network ID (e.g., an AID) as a result of becomingassociated with the wireless communication network.

In an embodiment, the method further includes the AP 114 receiving theUL SU packet 408 (FIG. 4), and block 1204 includes determining that theunassociated client station 154 requests to participate in the rangingmeasurement procedure based on receiving the UL SU packet 408. In otherembodiments, the method further includes the AP 114 receiving the UL MUpacket 608 (FIGS. 6, 9), and block 1204 includes determining that theunassociated client station 154 requests to participate in the rangingmeasurement procedure based on receiving the UL MU packet 608.

At block 1208, the AP 114 determines (e.g., the network interface device122 determines, the MAC processor 126 determines, etc.) a preliminary ID(e.g., a pre-AID) for the unassociated client station to be used by theunassociated client station during a ranging measurement session withthe AP device while the unassociated client station remains notassociated with the wireless communication network.

At block 1212, the AP 114 transmits (e.g., the network interface device122 transmits) a packet having the preliminary network ID (e.g., thepre-AID). The packet indicates that the AP 114 has assigned thepreliminary network ID to the unassociated client station 154 for useduring the ranging measurement session, according to an embodiment. Inan embodiment, block 1212 includes the MAC processor 126 generating anEFTM response frame that includes the pre-AID, and the PHY processor 130generating a PHY data unit that includes the EFTM frame.

In an embodiment, block 1212 includes the AP 114 generating andtransmitting (e.g., the network interface device 122 generating andtransmitting) the DL packet 404 (FIG. 4). In an embodiment, block 1212comprises transmitting the packet as an SU transmission. In anembodiment, block 1212 comprises generating a unicast frame thatincludes the pre-AID, and generating the packet to include the unicastframe. In another embodiment, block 1212 comprises generating abroadcast frame that includes the pre-AID, and generating the packet toinclude the broadcast frame.

In another embodiment, block 1212 includes the AP 114 generating andtransmitting (e.g., the network interface device 122 generating andtransmitting) the DL SU transmission 612 (FIG. 6). In anotherembodiment, block 1212 includes the AP 114 generating and transmitting(e.g., the network interface device 122 generating and transmitting) theM-BA 904 (FIG. 9). In an embodiment, block 1212 comprises transmittingthe packet within an MU transmission. In an embodiment, block 1212comprises generating respective unicast frames that include respectivepre-AIDs for respective unassociated client station 154, and generatingMU transmission to include the respective unicast frames.

At block 1216, after transmitting the packet at block 1212, the AP 114participates (e.g., the network interface device 122 participates) in anMU NDP ranging measurement session with a plurality of client stationsthat includes the unassociated client station. Participating in the MUNDP ranging measurement session includes the AP 114 transmitting (e.g.,the network interface device 122 transmitting) a trigger frame to promptthe plurality of client stations to simultaneously transmit respectiveNDPs as part of an uplink MU transmission corresponding to the MU NDPranging measurement session. The trigger frame includes the preliminarynetwork ID to prompt the unassociated client station to transmit an NDPas part of the uplink MU transmission. In an embodiment, the triggerframe includes multiple preliminary network IDs to prompt respectiveunassociated client stations to transmit respective NDPs as part of theuplink MU transmission.

FIG. 13 is a flow diagram of an example method 1300 for performing aranging measurement procedure, according to an embodiment. In someembodiments, the network interface device 162 of FIG. 1 is configured toimplement the method 1300. The method 1300 is described, however, in thecontext of the network interface device 162 merely for explanatorypurposes and, in other embodiments, the method 1300 is implemented byanother suitable device. For instance, in an embodiment, the networkinterface device 122 of FIG. 1, or another suitable WLAN networkinterface device is configured to implement the method 1300.

The method 1300 is implemented in conjunction with the procedures, frameformats, information element formats, etc., described above inconnection with one or more of FIGS. 2A, 2B, 3, 5A, 5B, 6, 7, 8A-C, and9, in various embodiments. In other embodiments, the method 1300 isimplemented in conjunction with suitable procedures, frame formats,information element formats, etc., different that those discussed abovein connection with FIGS. 2A, 2B, 3, 5A, 5B, 6, 7, 8A-C, and 9.

At block 1304, a first communication device receives (e.g., anunassociated client station 154 receives, the network interface device162 receives, etc.) a packet having a preliminary network ID (e.g., apre-AID). The packet indicates that the AP 114 has assigned thepreliminary network ID to the first communication device for use duringa ranging measurement session, according to an embodiment. In anembodiment, block 1304 includes the PHY processor 170 processing thepacket to extract an EFTM response frame that includes the pre-AID, andthe MAC processor 166 processing the EFTM response frame to determinethe pre-AID assigned to the unassociated client station 154.

In an embodiment, block 1304 includes the first communication devicereceiving (e.g., the unassociated client station 154 receiving, thenetwork interface device 162 receiving, etc.) the DL packet 404 (FIG.4). In an embodiment, block 1304 comprises receiving the packet as an SUtransmission. In an embodiment, block 1304 comprises receiving withinthe packet a unicast frame that includes the pre-AID. In anotherembodiment, block 1304 comprises receiving a broadcast frame thatincludes the pre-AID.

In another embodiment, block 1304 includes the first communicationdevice receiving (e.g., the unassociated client station 154 receiving,the network interface device 162 receiving, etc.) the DL SU transmission612 (FIG. 6). In another embodiment, block 1304 includes the firstcommunication device receiving (e.g., the unassociated client station154 receiving, the network interface device 162 receiving, etc.) theM-BA 904 (FIG. 9). In an embodiment, block 1304 comprises receiving thepacket within an MU transmission. In an embodiment, block 1304 comprisesreceiving a unicast frame with the MU transmission, the unicast frameaddressed to the first communication device and including the pre-AIDfor the first communication device.

In an embodiment, the method 1300 further includes the firstcommunication device generating and transmitting (e.g., the unassociatedclient station 154 generating and transmitting, the network interfacedevice 162 generating and transmitting, etc.) the UL SU packet 408 (FIG.4), and the packet received at block 1304 is responsive to the UL SUpacket 408. In other embodiments, the method further includes the firstcommunication device generating (e.g., the unassociated client station154 generating, the network interface device 162 generating, the MACprocessor 166 generating, etc.) a request frame that indicates that thefirst communication device wants to participate in a ranging measurementexchange; the method further includes the first communication devicetransmitting (e.g., the unassociated client station 154 transmitting,the network interface device 162 transmitting, the PHY processor 170transmitting, etc.) the request frame as part of the UL MU packet 608(FIGS. 6, 9); and the packet received at block 1304 is responsive to therequest frame in the UL MU packet 608.

At block 1308, after receiving the packet at block 1304, the firstcommunication device participates (e.g., the unassociated client station154 participates, the network interface device 162 participates, etc.)in an MU NDP ranging measurement session with the AP 114. Participatingin the MU NDP ranging measurement session includes receiving, at thecommunication device, a trigger frame from the AP 114, the trigger frameconfigured to prompt a plurality of communication devices, including thefirst communication device, to simultaneously transmit respective NDPsas part of an uplink MU transmission corresponding to the MU NDP rangingmeasurement session. The trigger frame includes the preliminary networkID assigned to the first communication device to prompt the firstcommunication device to transmit a first NDP as part of the uplink MUtransmission. Participating in the MU NDP ranging measurement sessionalso includes, in response to the trigger frame, transmitting, by thefirst communication device, the first NDP as part of the uplink MUtransmission.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any computer readable memory suchas on a magnetic disk, an optical disk, or other storage medium, in aRAM or ROM or flash memory, processor, hard disk drive, optical diskdrive, tape drive, etc. The software or firmware instructions mayinclude machine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for performing a ranging measurementprocedure, the method comprising: determining, at an access point (AP)device of a wireless communication network, that an unassociated clientstation requests to participate in a ranging measurement procedure withthe AP device, wherein the unassociated client station is not currentlyassociated with the wireless communication network and has not beenassigned, by the AP device, a network identifier (ID); determining, atthe AP device, a preliminary network ID for the unassociated clientstation, the preliminary network ID to be used by the unassociatedclient station during a ranging measurement session while theunassociated client station remains not associated with the wirelesscommunication network; transmitting, by the AP device, a packet havingthe preliminary network ID, wherein the packet indicates that the APdevice has assigned the preliminary network ID to the unassociatedclient station for use during the ranging measurement session; and aftertransmitting the packet having the preliminary network ID, participatingin, by the AP device, a multi-user (MU) null data packet (NDP) rangingmeasurement session with a plurality of client stations that includesthe unassociated client station, wherein participating in the MU NDPranging measurement session includes transmitting a trigger frame toprompt the plurality of client stations to simultaneously transmitrespective NDPs as part of an uplink MU transmission corresponding tothe MU NDP ranging measurement session, wherein the trigger frameincludes the preliminary network ID to prompt the unassociated clientstation to transmit an NDP as part of the uplink MU transmission.
 2. Themethod of claim 1, wherein transmitting the packet having thepreliminary network ID comprises: transmitting the packet as asingle-user (SU) transmission to the unassociated client station.
 3. Themethod of claim 2, wherein: the packet is a first packet; determiningthat the unassociated client station requests to participate in theranging measurement procedure with the AP device comprises receiving, atthe AP device, a second packet from the unassociated station as an SUtransmission, the second packet corresponding to a request toparticipate in a ranging measurement procedure; and the first packet istransmitted in response to receiving the second packet.
 4. The method ofclaim 2, wherein: the packet includes an information elementcorresponding to assignment of preliminary network IDs to unassociatedclient stations in connection with a ranging measurement procedure; andthe preliminary network ID is included in the information element. 5.The method of claim 1 wherein the AP assigns a value for the preliminarynetwork ID to the unassociated client station from a same set of networkID values that the AP assigns for network IDs to associated clientstations of the plurality of client stations.
 6. The method of claim 5wherein no two client stations from a group comprising the plurality ofclient stations and the unassociated client station are assigned a samevalue from the same set of network ID values.
 7. An apparatus,comprising: a network interface device associated with an access point(AP) device of a wireless communication network, wherein the networkinterface device includes one or more integrated circuits (ICs), andwherein the network interface device is configured to: determine that anunassociated client station requests to participate in a rangingmeasurement procedure with the AP device, wherein the unassociatedclient station is not currently associated with the wirelesscommunication network and has not been assigned, by the AP device, anetwork identifier (ID), determine a preliminary network ID for theunassociated client station, the preliminary network ID to be used bythe unassociated client station during a ranging measurement sessionwhile the unassociated client station remains not associated with thewireless communication network, transmit a packet having the preliminarynetwork ID, wherein the packet indicates that the AP device has assignedthe preliminary network ID to the unassociated client station for useduring the ranging measurement session, and after transmitting thepacket having the preliminary network ID, participate in a multi-user(MU) null data packet (NDP) ranging measurement session with a pluralityof client stations that includes the unassociated client station,wherein participating in the MU NDP ranging measurement session includestransmitting a trigger frame to prompt the plurality of client stationsto simultaneously transmit respective NDPs as part of an uplink MUtransmission corresponding to the MU NDP ranging measurement session,wherein the trigger frame includes the preliminary network ID to promptthe unassociated client station to transmit an NDP as part of the uplinkMU transmission.
 8. The apparatus of claim 7, wherein the networkinterface device is configured to: transmit the packet as a single-user(SU) transmission to the unassociated client station.
 9. The apparatusof claim 8, wherein: the packet is a first packet; the network interfacedevice is configured to determine that the unassociated client stationrequests to participate in the ranging measurement procedure with the APdevice comprises based on receiving a second packet from theunassociated station as an SU transmission, the second packetcorresponding to a request to participate in a ranging measurementprocedure; and the network interface device is configured to transmitthe first packet in response to receiving the second packet.
 10. Theapparatus of claim 8, wherein the network interface device is configuredto: generate the packet to include an information element correspondingto assignment of preliminary network IDs to unassociated client stationsin connection with a ranging measurement procedure; and generate theinformation element to include the preliminary network ID.
 11. Theapparatus of claim 7 wherein the AP assigns a value for the preliminarynetwork ID to the unassociated client station from a same set of networkID values that the AP assigns for network IDs to associated clientstations of the plurality of client stations.
 12. A method forperforming a ranging measurement procedure, the method comprising:receiving, at a first communication device, a packet having apreliminary network identifier (ID), wherein the packet indicates thatan access point (AP) device of a wireless communication network hasassigned the preliminary network ID to the first communication devicefor use during a ranging measurement session, wherein the firstcommunication device is not currently associated with the wirelesscommunication network and has not been assigned, by the AP device, anetwork ID; after receiving the packet having the preliminary networkID, participating in, by the first communication device, a multi-user(MU) null data packet (NDP) ranging measurement session with the APdevice, wherein participating in the MU NDP ranging measurement sessionincludes: receiving, at the first communication device, a trigger frameconfigured to prompt a plurality of communication devices, including thefirst communication device, to simultaneously transmit respective NDPsas part of an uplink MU transmission corresponding to the MU NDP rangingmeasurement session, wherein the trigger frame includes the preliminarynetwork ID to prompt the first communication device to transmit a firstNDP as part of the uplink MU transmission, and in response to thetrigger frame, transmitting, by the first communication device, thefirst NDP as part of the uplink MU transmission.
 13. The method of claim12 wherein the AP assigns a value for the preliminary network ID to thefirst communication device from a same set of network ID values that theAP assigns for network IDs to associated communication devices of theplurality of communication devices.
 14. The method of claim 12, whereinreceiving the packet having the preliminary network ID comprises:receiving the packet via a single-user (SU) transmission from the APdevice.
 15. The method of claim 14, wherein: the packet is a firstpacket; the method further comprises: transmitting, by the firstcommunication device, a second packet to the AP device as an SUtransmission, the second packet corresponding to a request toparticipate in a ranging measurement procedure; and the first packet isreceived in response to transmitting the second packet.
 16. The methodof claim 14, wherein: the packet includes an information elementcorresponding to assignment of preliminary network IDs to unassociatedclient stations in connection with a ranging measurement procedure; andthe preliminary network ID is included in the information element. 17.An apparatus, comprising: a network interface device associated with afirst communication device, wherein the network interface deviceincludes one or more integrated circuits (ICs), and wherein the networkinterface device is configured to: receive a packet having a preliminarynetwork identifier (ID), wherein the packet indicates that an accesspoint (AP) device of a wireless communication network has assigned thepreliminary network ID to the first communication device for use duringa ranging measurement session, wherein the first communication device isnot currently associated with the wireless communication network and hasnot been assigned, by the AP device, a network ID, after receiving thepacket having the preliminary network ID, participate in a multi-user(MU) null data packet (NDP) ranging measurement session with the APdevice, wherein network interface device is configured to, as part ofparticipating in the MU NDP ranging measurement session: receive atrigger frame configured to prompt a plurality of communication devices,including the first communication device, to simultaneously transmitrespective NDPs as part of an uplink MU transmission corresponding tothe MU NDP ranging measurement session, wherein the trigger frameincludes the preliminary network ID to prompt the first communicationdevice to transmit a first NDP as part of the uplink MU transmission,and in response to the trigger frame, transmit the first NDP as part ofthe uplink MU transmission.
 18. The apparatus of claim 17, wherein thenetwork interface device is configured to: receive the packet via asingle-user (SU) transmission from the AP device.
 19. The apparatus ofclaim 18, wherein: the packet is a first packet; the network interfacedevice is configured to: transmit a second packet to the AP device as anSU transmission, the second packet corresponding to a request toparticipate in a ranging measurement procedure; and the first packet isreceived in response to transmitting the second packet.
 20. Theapparatus of claim 18, wherein: the packet includes an informationelement corresponding to assignment of preliminary network IDs tounassociated client stations in connection with a ranging measurementprocedure; and the preliminary network ID is included in the informationelement.
 21. The apparatus of claim 17 wherein the AP assigns a valuefor the preliminary network ID to the first communication device from asame set of network ID values that the AP assigns for network IDs toassociated communication devices of the plurality of communicationdevices.